Field of the Invention
The present invention relates to a touch-panel liquid-crystal display device, and more particularly, to a touch-panel liquid-crystal display device in which a gap column spacer, which maintains a gap between two bonded substrates, and a push column spacer, which serves to sense a touch, have the same height, and in which the gap column spacer is located on a metal line so as to enable adjustment of the optimum amount of liquid crystals upon liquid-crystal dotting.
Discussion of the Related Art
With the development of multimedia, the importance of flat panel display devices is increasing. In response to this, flat panel display devices such as a liquid-crystal display device, a plasma display device, and an organic light-emitting display device have been commercialized.
Among these flat panel display devices, a liquid-crystal display device is widely used as a portable flat panel display device owing to several advantages thereof, such as high image quality, a low weight, a small thickness, and low power consumption, and in particular, is used for various applications such as a laptop computer, a computer monitor, and a television.
A touch-panel liquid-crystal display device having a touch panel stacked thereon has widely been used and is formed by stacking touch panels. When a user touches the touch panel with the hand, a stylus pen or the like, electrical characteristics such as resistance or capacitance vary at a touch point. The touch-panel liquid-crystal display device senses the touch point, thereby outputting information corresponding to the touch point or performing an arithmetic operation.
The touch-panel liquid-crystal display device described above is one of various user interfaces, and the application range thereof has expanded to small portable terminals, office equipment, mobile phones, and the like.
However, due to the fact that the touch panel is separately stacked on the liquid crystal display device, there is a limitation in achieving thinness due to an increase in overall thickness, light transmission efficiency is reduced when light passes through the stacked panel, and production costs are increased.
In order to address the problems described above, an in-cell-type touch-panel liquid-crystal display device has been proposed, in which a touch sensor is mounted in a pixel area of the liquid-crystal display device.
FIG. 1 is a cross-sectional view of an in-cell-type touch-panel liquid-crystal display device 10 according to a related art.
Referring to FIG. 1, the in-cell-type touch-panel liquid-crystal display device 10 includes a thin-film transistor array substrate 11, a color filter array substrate 21, and a liquid-crystal layer 17 disposed between the thin-film transistor array substrate 11 and the color filter array substrate 21.
The thin-film transistor array substrate 11 includes a gate line 12 disposed in a given direction, a gate insulation layer 18 disposed to cover the gate line 11, a data line 13 disposed on the gate insulation layer 18 in a direction orthogonal to the gate line 12, and a lower planarization layer 14, an insulation layer 15, and a lower alignment layer 16b, which are sequentially formed on the data line 13.
The color filter array substrate 21 includes a black matrix 22 for preventing color mixing between sub-pixels, a color filter layer 23 formed in each pixel area between neighboring portions of the black matrix 22, an upper planarization layer 24 formed on the color filter layer 23, a push column spacer 25 and a gap column spacer 26, which are formed on the upper planarization layer 24 so as to correspond to each intersection of the gate line 12 and the data line 13 of the thin-film transistor array substrate 11, and an upper alignment layer 16a formed over the entire surface on which the push column spacer 25 and the gap column spacer 26 have been formed.
Here, the gap column spacer 26 is formed so as to be brought into contact with the thin-film transistor array substrate 11 and serves to maintain a gap between the thin-film transistor array substrate 11 and the color filter array substrate 21.
The push column spacer 25 is formed so as to be spaced apart from the thin-film transistor array substrate 11.
That is, the height of the gap column spacer 26 is higher than the height of the push column spacer 25.
However, the touch-panel liquid-crystal display device described above has the following problems and limitations.
First, because the gap column spacer and the push column spacer are formed to have different heights by photo-lithography and etching processes using a half-tone mask, uniform adjustment and management of the height difference are difficult during an exposure process.
Second, when or after printing the upper alignment layer, foreign substances may be generated due to the height difference between the gap column spacer and the push column spacer, which may cause deterioration in image quality.
Third, due to the height difference between the gap column spacer and the push column spacer, it is impossible or difficult to adjust the optimum amount of liquid crystals when the liquid crystals are disposed.